1. Technical Field
The technique disclosed in this specification relates to a switching device and a method of manufacturing the same.
2. Description of Related Art
Japanese Patent Application Publication No. 2015-118966 (JP 2015-118966 A) discloses a switching device including a gate electrode disposed in a trench. The switching device includes an n-type first semiconductor region (source region), a p-type body region, and an n-type second semiconductor region (drift region). The first semiconductor region, the body region, and the second semiconductor region are in contact with a gate insulating layer at a side surface of the trench. Further, the switching device includes a p-type bottom semiconductor region that is in contact with a bottom surface of the trench. The switching device further includes a p-type connection semiconductor region extending along a part of the side surface of the trench. The connection semiconductor region is connected to the body region and the bottom semiconductor region. By the connection semiconductor region, the potential of the bottom semiconductor region is controlled to be substantially equal to that of the body region. When the switching device is turned off, a depletion layer extends from the bottom semiconductor region into the second semiconductor region. By the depletion layer, electric field concentration in the vicinity of the bottom semiconductor region (i.e., in the vicinity of the bottom of the trench) is suppressed.